I run into a problem when using the Django admin. I'm building a small ScrumBoard. It has projects, with statuses, stories and tasks.
Consider the following model:
#python_2_unicode_compatible
class Project(models.Model):
name = models.CharField(max_length=100)
class Meta:
verbose_name = _('Project')
verbose_name_plural = _('Projects')
def __str__(self):
return self.name
#python_2_unicode_compatible
class Status(models.Model):
name = models.CharField(max_length=64) # e.g. Todo, In progress, Testing Done
project = models.ForeignKey(Project)
class Meta:
verbose_name = _('Status')
verbose_name_plural = _('Statuses')
def __str__(self):
return self.name
#python_2_unicode_compatible
class Story(models.Model):
"""Unit of work to be done for the sprint. Can consist out of smaller tasks"""
project = models.ForeignKey(Project)
name=models.CharField(max_length=200)
description=models.TextField()
status = models.ForeignKey(Status)
class Meta:
verbose_name = _('Story')
verbose_name_plural = _('Stories')
# represent a story with it's title
def __str__(self):
return self.name
The problem: when an admin user creates a story he will see statuses from all the projects instead of the status from one project.
To filter statuses by project, you need your story to already exist so django know which project we are talking about. If you set status nullalble, you can do like this (implying, you do save and continue on first save to set status)
class StatusAdmin(admin.ModelAdmin):
def get_form(self, request, obj=None, **kwargs):
form = super(StatusAdmin, self).get_form(request, obj, **kwargs)
if obj and obj.project:
form.base_fields['status'].queryset = \
form.base_fields['status'].queryset.filter(project=obj.project)
elif obj is None and 'status' in form.base_fields: # on creation
del form.base_fields['status']
return form
You will need something like django-smart-selects
Related
I am querying select related between two models Requirements and Badge Requirement has a related badge indicated by badge_id Models are,
class Badge(models.Model):
level = models.PositiveIntegerField(blank=False, unique=True)
name = models.CharField(max_length=255, blank=False , unique=True)
description = models.TextField(blank=True)
class Meta:
verbose_name = _("Badge")
verbose_name_plural = _("Badges")
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse("Badge_detail", kwargs={"pk": self.pk})
""" Requirement Model for requirements """
class Requirement(models.Model):
number = models.PositiveIntegerField(blank=False)
badge = models.ForeignKey(Badge, on_delete=models.CASCADE)
name = models.CharField(max_length=255)
description = models.TextField(blank=True)
class Meta:
verbose_name = _("Requirement")
verbose_name_plural = _("Requirements")
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse("Requirement_detail", kwargs={"pk": self.pk})
In My view I try to join both tables and retrieve. It is,
""" ajax requirements in requirements table """
def get_requirements(request):
requirements = Requirement.objects.all().select_related('badge').values()
print(requirements)
return JsonResponse(list(requirements), safe=False)
The result is,
to the frontend,
to the backend,
Why does it not give me both tables' values?
Best way to achieve that is using Serializers which are the key component to deal with transforming data from models to JSON and the inverse:
To use this approach you can create the following serializers:
yourapp.serializers.py
from rest_framework.serializers import ModelSerializer
from yourapp.models import Requirement, Badge
class BadgeSerializer(ModelSerializer):
class Meta:
model = Badge
fields = '__all__'
class RequirementSerializer(ModelSerializer):
badge = BadgeSerializer()
class Meta:
model = Requirement
fields = '__all__'
After that you should go to your views.py file and do the following changes:
from yourapp.serializers import RequirementSerializer
def get_requirements(request):
reqs = Requirement.objects.select_related('badge')
return JsonResponse(RequirementSerializer(reqs, many=True), safe=False)
In this way you will have a more flexible way to add or remove fields from the serializer, and your application is also going to be more decoupled and easy to maintain.
I have two model classes. They are not related models (no relationship).
# models.py
class Model1(models.Model):
description = models.TextField()
option = models.CharField(max_length=64, blank=False)
def __str__(self):
return self.option
class Model2(models.Model):
name = models.CharField(max_length=64, blank=False)
def __str__(self):
return self.name
I have respective form from where I am submitting and saving data in my table. I want to use my Model2 data to fill-in 'option' field as select field, so I am introducing below init method.
# forms.py
class Model1Form(forms.ModelForm):
def __init__(self, *args, **kwargs):
all_options = Model2.objects.all()
super(Model1Form, self).__init__(*args, **kwargs)
self.fields['option'].queryset = all_options
class Meta:
model = Model1
fields = ('description', 'option')
It does not render the dropdown on my template, so I am wondering whether it is right way to address the issue (acknowledging that models are not related to each other).
2 Classes involved in question class Appointment and class Service
appointmentApp.models class Service
class Service(models.Model):
service_name = models.CharField(max_length=15, blank=False)
service_time = models.IntegerField(blank=False)
def __str__(self):
return self.service_name
class Meta:
verbose_name_plural = "Services"
appointmentApp/models.py class Appointment
class Appointment(models.Model):
service_chosen = models.ManyToManyField(Service, blank=False)
total_time = models.IntegerField(blank=False, null=False, default=0)
#will add up the amount of time needed for each service
def save(self, *args, **kwargs):
self.total_time += Service.objects.all().aggregate(total_time=Sum('service_time'))['total_time']
super(Appointment, self).save(*args, **kwargs)
def __str__(self):
return self.client_dog_name
Services are chosen through a multiplechoice field and on save the service_chosen's service_time are added up
but what my save function is doing instead is adding up all the existing service.service_time instead of the ones selected, why is this happening?
ManyToManyFields are saved after the containing instance is saved, you need to create a signal handler to perform this update on m2m_changed
from django.db.models.signals import m2m_changed
class Appointment(models.Model):
...
def service_chosen_changed(sender, instance=None, action=None, **kwargs):
if action == 'post_add':
instance.total_time = instance.service_chosen.aggregate(total_time=Sum('service_time'))['total_time']
instance.save()
m2m_changed.connect(service_chosen_changed, sender=Appointment.service_chosen.through)
I am trying to test my Models Project, Category and Tag. I'm running into an issue when trying to add tags to my project model.
It won't allow me to do it in the Project model itself for eg.
self.project = Project.objects.create(
...
tags=Tag.objects.create("HTML5"),
)
Django docs suggest the I do it as below. However I can't "add" the Tag without saving the model and I can't save the model without adding the Tag
Tests
class ProjectTests(TestCase):
def setUp(self):
self.tag = Tag.objects.create(name="HTML5")
self.project = Project(
title="Oaks on Main Shopping Center",
url="www.oaksonmain.co.za",
image=SimpleUploadedFile(
name="test-image.jpg",
content=open(
"static\\images\\test_images\\florian-olivo-4hbJ-eymZ1o-unsplash (1).jpg", "rb"
).read(),
content_type="image/jpeg",
),
description="Beautiful website created for Oaks on Main Shopping Center in Knysna!",
category=Category.objects.create(name="Website"),
)
self.project.save() <- Problem here
self.project.tags.add(self.tag) <- Problem here
def test_project_model(self):
self.assertEqual(f"{self.project.title}", "Oaks on Main Shopping Center")
self.assertEqual(f"{self.project.url}", "www.oaksonmain.co.za")
self.assertEqual(
f"{self.project.description}",
"Beautiful website created for Oaks on Main Shopping Center in Knysna!",
)
self.assertEqual(self.tags.count(), 3)
self.assertEqual(self.category.count(), 1)
self.assertEqual(self.image.count(), 1)
def test_project_listview(self):
resp = self.client.get(reverse("index"))
self.assertEqual(resp.status_code, 200)
self.assertContains(resp, self.project.title)
self.assertTemplateUsed(resp, "page/index.html")
Models
class Project(models.Model):
class Meta:
ordering = ["-id"] # Always show latest projects first
verbose_name_plural = "Projects"
title = models.CharField(max_length=50)
url = models.URLField()
image = models.ImageField(upload_to=f"{title}/")
description = models.TextField()
category = models.ForeignKey("Category", on_delete=models.PROTECT, related_name="categories")
tags = models.ManyToManyField("Tag", verbose_name="tags")
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse("index")
class Category(models.Model):
class Meta:
ordering = ["name"]
verbose_name_plural = "Categories"
name = models.CharField(max_length=20)
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse("index")
class Tag(models.Model):
class Meta:
ordering = ["name"]
verbose_name_plural = "Tags"
name = models.CharField(max_length=10)
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse("index")
You can first save the tag or the model object, and then later you link the tag as (one of) tags of that Project, so:
html5_tag, __ = Tag.objects.get_or_create(name='HTML5')
self.project = Project.objects.create(
# no tags=…
)
self.project.tags.add(html5_tag)
Your ImageField also should work with a callable for the upload_to=… parameter, so:
class Project(models.Model):
# …
def upload_image(self, filename):
return f'{self.title}/{filename}'
image = models.ImageField(upload_to=upload_image)
# …
I am new to Django and still learning. I am looking to keep track of how many events I have under a test. My current model looks like
class Test(models.Model):
name = models.CharField(max_length=255)
description = models.CharField(max_length=255, blank=True)
num_of_events = models.IntegerField(default=0)
class Meta:
verbose_name = 'Test'
verbose_name_plural = 'Tests'
def __str__(self):
return self.name
class Event(models.Model):
name = models.CharField(max_length=255)
test = models.ForeignKey(Test,on_delete=models.CASCADE)
class Meta:
verbose_name = 'Event'
verbose_name_plural = 'Events'
def __str__(self):
return self.name
def save(self):
obj, created = Test.objects.update_or_create(name=self.test)
obj.num_of_events += 1
super().save()
def delete(self):
self.test.num_of_events -= 1
super().delete()
I thought I could just override the save() function but it does not update on the admin panel and still shows 0.
I am trying to figure out what I am doing wrong.
EDIT: admin.py
class TestAdmin(admin.ModelAdmin):
list_display = ('name', 'description', 'num_of_events')
fieldsets = [
(None, {'fields': ('name', 'description')})
]
class EventsAdmin(admin.ModelAdmin):
pass
class PropertyAdmin(admin.ModelAdmin):
list_display = ('name', 'property_type', 'expected_value')
admin.site.register(Test, TestAdmin)
admin.site.register(Event, EventsAdmin)
admin.site.register(Property, PropertyAdmin)
You forget to save the Test object. For example with:
class Event(models.Model):
# …
def save(self):
if self.test_id is not None:
obj = self.test
obj.num_of_events += 1
obj.save()
super().save()
def delete(self):
if self.test_id is not None:
self.test.num_of_events -= 1
self.test.save()
super().delete()
But regardless, storing the number of items is usually not a good idea. Say that you change the .test of a given Event, then you need to subtract from the old Test and add to the new Test. Furthermore ORM operations in bulk, like .update(..) circumvent .save() and signals, so it will be hard or impossible to keep this correct.
The point is that you do not need to store the number of Events. Indeed, you can simply obtain these with:
from django.db.models import Count
Test.objects.annotate(number_of_events=Count('event'))
The Test objects that arise from this queryset will have an extra attribute .number_of_events that contains the number of related Event ojbects.